[Esr-users] blockage in Hall C coldl return

[Paul Brindza]

Greetings

The Hall C magnets filled over the weekend but the magnets are at much 
higher pressure than usual.

They are running at 1.75 Bar instead of 1.5 Bar.

The cold return passage in the cryo transfer line appears to be 
partially blocked.

We are searching the archive for an event that could have caused this.

We are looking thru the archive during the ESR shutdown and long idle 
period  to see if the pressure in the transfer line ever went negative.

There were long periods when the transfer line was isolated and both 
supply and return valves were shut off.

During the early stages of the Hall C recovery when we were starting to 
cool down and the transfer line cold return was closed is the dangerous 
period where contamination could enter the return transfer line while 
the supply is cooling..

This happened at least once before several years ago.

We may have to perform some pressure measurements in Hall C to isolate 
the partially blocked section.

We will know more soon.

Assuming contamination ice is determined to be the cause of the partial 
blockage we will eventually have to take Hall C off line and warm the 
blocked section of transfer line to remove the plug.

Cheers


Paul